It is estimated that in the United States alone, as of the mid-1990s, there were 25,000,000 people a day who suffered from some kind of back pain and that as many as nine out of ten Americans will suffer back pain at some time in their lives. The resultant total economic burden on industry in the United States is estimated at $40 to $50 billion annually.
One approach to relieving back pain and cervical pain is through exercise or therapeutic movement, and a substantial number of exercise devices and machines have been developed for exercising the back. However, many of these devices are unsuitable for persons suffering from serious back pain because use thereof tends to increase the pain and/or because there is danger of injury (or further injury) to the back, e.g., to the spine or to the supporting muscles.
One approach to exercising of the back and other parts of the body involves the use of passive exercise machines, i.e., machines that exercise muscles of the user (e.g., the back and abdominal muscles) without any active effort on the part of the user. A number of these devices and machines include separate support sections for supporting different parts of the body (e.g., the head and upper torso are supported on one section and the lower torso and legs on a second section) and are motorized so that, e.g., while the user lies flat on his or her back, the lower torso and legs are moved as a unit with respect to the upper torso and head which remain stationary, so as to provide automatic side flexion. Such machines include conventional “toning tables” as well as specially designed devices such as the “electric flexion distraction table” made by Health Care Manufacturing of Springfield, Mo. and the SPINALATOR® machine made by the Chattanooga Group, Inc. of Hixon, Tenn.
Patented devices of interest include those disclosed in U.S. Pat. No. 5,500,002 (Riddle et al.); U.S. Pat. No. 5,320,641 (Riddle et al.); U.S. Pat. No. 5,123,916 (Riddle et al.); U.S. Pat. No. 4,827,913 (Parker); U.S. Pat. No. 4,144,880 (Daniels); U.S. Pat. No. 6,086,550 (Richardson); U.S. Pat. No. 4,953,541 (Parker, Jr.); U.S. Pat. No. 5,044,359 (Reinert); U.S. Pat. No. 5,171,260 (Mcllwain); U.S. Pat. No. 5,035,234 (Forsythe); and U.S. Pat. No. 3,674,017 (Stefani, Jr.). Briefly considering some of these patents, the Riddle et al. patents all disclose passive exercise devices designed for the lower back region. The devices feature two sets of support means, one for the upper body and one for the lower body. The device is designed such that either one, or both of the two support means may be pivoted up or down. The Parker patent discloses a passive exercise device which includes interchangeable components adapted to be attached to the table apparatus. The device is deigned to provide leg exercises in a variety of different positions. The Daniels patent discloses a passive traction/motion device. A cervical traction device is also provided. The Richardson patent discloses a passive exercise device in which the patient may be reclined in the so-called “90/90” position described below. The legs of the patient are placed in a leg rest which may be removed from a table portion. The device provides a variable speed rocking motion (in an elliptical path) to the legs and torso of the user.
An important advance in continuous passive motion machines is disclosed in commonly assigned U.S. Pat. No. 6,692,451 (Splane). This patent is discussed in more detail below.